Temperature control systems which utilize a plurality of heating or cooling devices to maintain the temperature at some location proximate a predetermined desired temperature or setpoint are broadly old in the art. A copending application of Ronald Benton et al, Ser. No. 202,985 filed Nov. 3, 1980 describes such a system. In the prior art systems, it is normal to have a number of stages of heating and cooling each of which is turned "on" and "off" at predetermined temperature variations from the setpoint. For example, in a chiller system, a first stage of cooling would be turned "on" when the temperature varied from the setpoint by a first amount with a second chiller being turned "on" when the temperature reached a second value with respect to the setpoint, the third being turned "on" as the temperature increased to a certain point even further away from the setpoint and so on through the number of stages that were provided. Likewise, when the temperature began to decline, the last stage would be turned "off" at a first temperature from the setpoint and successive stages in each being turned "off" at different temperatures until the proper temperature was again reached. One difficulty with such a system occurs when there are rather rapid changes in the load causing rapid temperature variations. When this occurs, the various stages must turn "on" and "off" in rather rapid succession resulting in multistage cycling that is undesirable and possibly damaging to the compressors.